Electromagnetic radiation absorbers typically are nonconductive composites of one or more kinds of dissipative particles dispersed in dielectric binder materials. The absorption performance of the composite absorber depends predominantly on the electromagnetic interactions of the individual particles with each other and with the binder. Various types of particles have been used including metals, magnetic metals, semiconductors, ferrites, and carbon; similarly, many kinds of dielectric binders have been used, including polymers and ceramics.
A common application of an absorber is a cover for a structure which would otherwise reflect radiation. The thickness of the cover and its mounting affect the desired absorption or suppression, but some composite materials are difficult to apply permanently to many structures, decreasing the performance of the cover. Also, the cover often must prevent moisture or other contaminants from reaching the underlying structure. Often a suppression cover must be applied in adverse weather by untrained personnel, but it should maintain a watertight seal, withstand temperature fluctuations, protect against corrosion, and the like.
Many covers contain absorbers which are designed for direct contact with a reflective conductor. If the conductor is the covered structure itself, gaps between the suppression cover and the conductive surface may significantly reduce the suppression performance of the cover.